That's right. For even if some kind of god exists the believer has no reasonable way to know anything about such a god, hence a theistic kind of agnosticism. dguller expressed this cogent argument very well in the comments:

One question that I have for religious believers is how they would distinguish between the following:

(1) An all-powerful deity created and guides the universe ultimately towards a good purpose;

and

(2) An all-powerful deity created and guides the universe ultimately towards an evil purpose, but have chosen to maliciously presented himself as benevolent to play a trick on created beings.

I mean, since believers are big on creating conceptual space to make their positions logically POSSIBLE, then it is also possible that God is a Cosmic Trickster who takes pleasure in fooling them.

How could one refuse (2)? Only based upon one's religious beliefs that (1) must be true. The problem is that one's beliefs that (1) must be true could be part of the cosmic joke in scenario (2), and thus there is no real way to differentiate between (1) and (2) for a religious believer.

Believers can say "I know that I know that I know all they want to," but their knowing can be accounted for by (2) since such a possible god is a trickster. Likewise, any claim of a true religious experience according to Plantinga's Reformed Epistemology cannot overcome scenario (2).

And so my friends there can be no reason given scenario (2) to think that it won't be skeptics like ME who will be rewarded in heaven rather than believers like YOU! As far as we know believers like YOU will end up in hell.

Christians, better switch sides now while you can. Hurry before you die. It could be today.